Bias supply with a single controlled switch

ABSTRACT

Bias supplies, plasma processing systems, and associated methods are disclosed. One bias supply comprises a first inductor coupled between a first node of a switch and an output node where a first node of a second inductor is coupled to one of the output node or the first node of the switch. A voltage source is coupled between a second node of the switch and a second node of the second inductor. A connection is made between the return node and one of the second node of the switch and the second node of the second inductor. The bias supply also comprises a controller configured to cause an application of the periodic voltage between the output node and the return node by repeatedly closing the switch so current through the switch completes a full cycle.

CLAIM OF PRIORITY UNDER 35 U.S.C. § 119

The present application for patent claims priority to ProvisionalApplication No. 62/873,680 entitled “A SINGLE CONTROLLED SWITCH, SINGLESUPPLY EV SOURCE WITH ION CURRENT COMPENSATION” filed Jul. 12, 2019 andassigned to the assignee hereof and hereby expressly incorporated byreference herein.

BACKGROUND Field

The present invention relates generally to power supplies, and morespecifically to power supplies for applying a voltage for plasmaprocessing.

Background

Many types of semiconductor devices are fabricated using plasma-basedetching techniques. If it is a conductor that is etched, a negativevoltage with respect to ground may be applied to the conductivesubstrate so as to create a substantially uniform negative voltageacross the surface of the substrate conductor, which attracts positivelycharged ions toward the conductor, and as a consequence, the positiveions that impact the conductor have substantially the same energy.

If the substrate is a dielectric, however, a non-varying voltage isineffective to place a voltage across the surface of the substrate. Butan alternating current (AC) voltage (e.g., high frequency AC or radiofrequency (RF)) may be applied to the conductive plate (or chuck) sothat the AC field induces a voltage on the surface of the substrate.During the positive peak of the AC cycle, the substrate attractselectrons, which are light relative to the mass of the positive ions;thus, many electrons will be attracted to the surface of the substrateduring the positive peak of the cycle. As a consequence, the surface ofthe substrate will be charged negatively, which causes ions to beattracted toward the negatively-charged surface during the rest of theAC cycle. And when the ions impact the surface of the substrate, theimpact dislodges material from the surface of the substrate—effectuatingthe etching.

In many instances, it is desirable to have a narrow ion energydistribution, but applying a sinusoidal waveform to the substrateinduces a broad distribution of ion energies, which limits the abilityof the plasma process to carry out a desired etch profile. Knowntechniques to achieve a narrow ion energy distribution are expensive,inefficient, difficult to control, and may adversely affect the plasmadensity. As a consequence, these known techniques have not beencommercially adopted. Accordingly, a system and method are needed toaddress the shortfalls of present technology and to provide other newand innovative features.

SUMMARY

An aspect of some implementations disclosed herein address the abovestated needs by utilizing switching frequency as a means of controltogether with a single controlled switch in a resonant circuit requiringonly one variable voltage supply to enable a drastically simplifiedcircuit to provide a desired narrow energy distribution.

Another aspect may be characterized as a power supply that comprises anoutput node, a return node, a switch, a first inductor, a secondinductor, and a voltage source. The first inductor is coupled between afirst node of the switch and the output node and a first node of asecond inductor is coupled to one of the output node or the first nodeof the switch. A voltage source is coupled between a second node of theswitch and a second node of the second inductor and a connection is madebetween the return node and one of the second node of the switch and thesecond node of the second inductor. A controller is configured to causean application of the periodic voltage between the output node and thereturn node by repeatedly closing the switch for a time just long enoughfor current through the switch to complete a full cycle from zero to apeak value, back to zero, to a peak value in an opposite direction andback to zero.

Yet another aspect may be characterized as a power supply comprising anoutput node, return node, a switch, a transformer, and a voltage source.A first node of a primary winding of the transformer is coupled to afirst node of the switch, a first node of a secondary winding of thetransformer is coupled to the output node, and a second node of thesecondary winding of the transformer is coupled to the return node. Avoltage source is coupled between a second node of the switch and asecond node of the primary winding of the transformer. The power supplyalso comprises a controller configured to cause an application of theperiodic voltage between the output node and the return node byrepeatedly closing the switch for a time just long enough for currentthrough the switch to complete a full cycle from zero to a peak value,back to zero, to a peak value in an opposite direction and back to zero.

Another aspect disclosed herein is a plasma processing system thatcomprises a plasma chamber and a bias supply. The plasma chambercomprises a volume to contain a plasma, an input node, and a returnnode. The bias supply includes a switch, a first inductor, a secondinductor, and a voltage source. The first inductor is coupled between afirst node of the switch and the input node of the plasma chamber and afirst node of a second inductor is coupled to one of the input node ofthe chamber or the first node of the switch. The voltage source iscoupled between a second node of the switch and a second node of thesecond inductor. A connection is made between the return node and one ofthe second node of the switch or the second node of the second inductor.The plasma processing system also comprises means for controlling theswitch and voltage source to achieve a desired waveform of a voltage ofa plasma load when the plasma is in the plasma chamber.

Yet another aspect may be characterized as a plasma processing systemcomprising a plasma chamber and a bias supply. The plasma processingchamber comprises a volume to contain a plasma, an input node, and areturn node, and the bias supply comprises a switch, a transformer, anda voltage source. A first node of a primary winding of the transformeris coupled to a first node of the switch, a first node of a secondarywinding of the transformer is coupled to the input node of the plasmachamber, and a second node of the secondary winding of the transformeris coupled to the return node. The voltage source is coupled between asecond node of the switch and a second node of the primary winding ofthe transformer. The plasma processing system also includes means forcontrolling the switch and voltage source to achieve a desired waveformof a voltage of a plasma load when the plasma is in the plasma chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram depicting an exemplary plasma processingenvironment in which bias supplies disclosed herein may be utilized;

FIG. 2 is a schematic diagram depicting an exemplary bias supply;

FIG. 3 is a schematic diagram electrically representing aspects of aplasma processing chamber;

FIG. 4 is a timing diagram depicting timing of electrical aspects of thebias supply in FIG. 2 when operated with the plasma processing chamberin FIG. 3;

FIG. 5A is a graphical depiction of sheath voltage versus time and aresulting ion flux versus ion energy;

FIG. 5B is a graph of a periodic voltage waveform that may produce thesheath voltage depicted in FIG. 5A;

FIG. 6A depicts another sheath voltage and a resulting ion flux versusion energy;

FIG. 6B is a graph of a periodic voltage waveform that may produce thesheath voltage depicted in FIG. 6A;

FIG. 7A depicts yet another sheath voltage and a resulting ion fluxversus ion energy;

FIG. 7B is a graph of a periodic voltage waveform that may produce thesheath voltage depicted in FIG. 7A;

FIG. 8 includes graphs depicting a periodic voltage waveform that may beapplied by the bias supply of FIG. 2 and a corresponding sheath voltage;

FIG. 9 includes graphs depicting another periodic voltage waveform thatmay be applied by the bias supply of FIG. 2 and a corresponding sheathvoltage;

FIG. 10 includes graphs depicting another periodic voltage waveform thatmay be applied by the bias supply of FIG. 2 and a corresponding sheathvoltage;

FIG. 11 is a schematic diagram depicting another exemplary bias supply;and

FIG. 12 includes graphs depicting a periodic voltage waveform that maybe applied by the bias supply of FIG. 11 and a corresponding sheathvoltage;

FIG. 13 includes graphs depicting another periodic voltage waveform thatmay be applied by the bias supply of FIG. 11 and a corresponding sheathvoltage;

FIG. 14 includes graphs depicting yet another periodic voltage waveformthat may be applied by the bias supply of FIG. 11 and a correspondingsheath voltage;

FIG. 15A is a flowchart depicting a method that may be traversed inconnection with several embodiments;

FIG. 15B is a flowchart depicting another method that may be traversedin connection with several embodiments;

FIG. 16A is a schematic diagram depicting an exemplary bias supply;

FIG. 16B is a schematic diagram depicting another exemplary bias supply;

FIG. 16C is a schematic diagram depicting another exemplary bias supply;

FIG. 16D is a schematic diagram depicting another exemplary bias supply;

FIG. 16E is a schematic diagram depicting another exemplary bias supply;

FIG. 16F is a schematic diagram depicting another exemplary bias supply;

FIG. 17 is a block diagram depicting components that may be utilized toimplement control aspects disclosed herein.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

Preliminary note: the flowcharts and block diagrams in the followingFigures illustrate the architecture, functionality, and operation ofpossible implementations of systems, methods and computer programproducts according to various embodiments. In this regard, some blocksin these flowcharts or block diagrams may represent a module, segment,or portion of code, which comprises one or more executable instructionsfor implementing the specified logical function(s). It should also benoted that, in some alternative implementations, the functions noted inthe block may occur out of the order noted in the figures. For example,two blocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustrations,and combinations of blocks in the block diagrams and/or flowchartillustrations, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

For the purposes of this disclosure, source generators are those whoseenergy is primarily directed to generating and sustaining the plasma,while “bias supplies” are those whose energy is primarily directed togenerating a surface potential for attracting ions and electrons fromthe plasma.

Described herein are several embodiments of novel bias supplies that maybe used to apply a periodic voltage function to a substrate support in aplasma processing chamber.

Referring first to FIG. 1, shown is an exemplary plasma processingenvironment (e.g., deposition or etch system) in which bias supplies maybe utilized. The plasma processing environment may include many piecesof equipment coupled directly and indirectly to a plasma chamber 101,within which a volume containing a plasma 102 and workpiece 103 (e.g., awafer) is contained. The equipment may include vacuum handling and gasdelivery equipment (not shown), one or more bias supplies 108, one ormore source generators 112, and one or more source matching networks113. In many applications, power from a single source generator 112 isconnected to one or multiple source electrodes 105. The source generator112 may be a higher frequency RF generator (e.g. 13.56 MHz to 120 MHz).The electrode 105 generically represents what may be implemented with aninductively coupled plasma (ICP) source, a dual capacitively-coupledplasma source (CCP) having a secondary top electrode biased at anotherRF frequency, a helicon plasma source, a microwave plasma source, amagnetron, or some other independently operated source of plasma energy.

In variations of the system depicted in FIG. 1, the source generator 112and source matching network 113 may be replaced by, or augmented with, aremote plasma source. And other variations of the system may includeonly a single bias supply 108.

While the following disclosure generally refers to plasma-based waferprocessing, implementations can include any substrate processing withina plasma chamber. In some instances, objects other than a substrate canbe processed using the systems, methods, and apparatus herein disclosed.In other words, this disclosure applies to plasma processing of anyobject within a sub-atmospheric plasma processing chamber to affect asurface change, subsurface change, deposition or removal by physical orchemical means.

Referring to FIG. 2, shown is an exemplary bias supply 208 to apply aperiodic voltage function. As shown, the bias supply 208 includes anoutput 210 (also referred to as an output node 210), a switch 220 and avoltage source 230. In addition, a first inductor 240 is coupled betweenthe switch and the output and a second inductor 250 is coupled betweenthe voltage source and the output. Also shown is a controller 260 thatis configured to open and close the switch 220 to produce a voltage atthe output as described further herein. For example, the controller 260may be configured to cause an application of the periodic voltagebetween the output 210 (also referred to as an output node 210) and theground connection 270 (also referred to as a return node 270) byrepeatedly closing the switch for a time just long enough for currentthrough the switch to complete a full cycle from zero to a peak value,back to zero, to a peak value in an opposite direction and back to zero.Current delivered to the load through output 210 is returned to the biassupply 208 through the ground connection 270 that is common with theload.

Referring briefly to FIG. 3, shown is a schematic drawing thatelectrically depicts aspects of a plasma load within the plasma chamber101. As shown, the plasma chamber 101 may be represented by a chuckcapacitance C_(ch) (that includes a capacitance of a chuck and workpiece103) that is positioned between an input 310 (also referred to as aninput node 310) to the plasma chamber 101 and a node representing avoltage, Vs, at a surface of the substrate (also referred to herein as asheath voltage). In addition, a return node 307 (which may be aconnection to ground) is depicted. The plasma 102 in the processingchamber is represented by a parallel combination of a sheath capacitanceC_(S), a diode, and a current source. The diode represents thenon-linear, diode-like nature of the plasma sheath that results inrectification of the applied AC field, such that a direct-current (DC)voltage drop, appears between the workpiece 103 and the plasma 102.

Referring again to FIG. 2, the switch 220 (like most field-effectswitches) includes a body diode allowing for reverse current flow evenwhen the switch is not controlled to be in an on state. Applicant hasfound that the body diode may be used as an advantage in that the switch220 (by virtue of the body diode) can be turned off any time during afirst reversal of current through the switch; thus, reducing the timingcriticality of the control. Although other types of switches may beused, the switch may be realized by silicon carbide metal-oxidesemiconductor field-effect transistors (SiC MOSFETs). It should berecognized that a drive signal 211 from the controller may be electricalor optical. It should also be understood that the switches depicted inthe other bias supplies disclosed herein (e.g., in FIG. 11, and FIGS.16A-F) may also include a body diode, and those switches of the otherbias supply may be driven by a drive signal 211.

Referring to FIG. 4, shown are waveforms depicting electrical aspects ofthe bias supply 208 and plasma processing chamber 101 when ion current,I_(ion), is properly compensated, which happens when the current,i_(L2), through the second inductor, L₂, equals the ion current,I_(ion). An aspect of the present disclosure addresses the problem ofhow to adjust the current, i_(L2), through L₂ to be equal to the ioncurrent I_(ion). As shown in FIG. 4, the switch 220 (also referred toherein as switch, S) may be controlled so that current through firstinductor 240, and hence the switch 220, completes a full cycle from zeroto a peak value, back to zero, to a peak value in an opposite directionand back to zero. It should be recognized the peak value the current,i_(L2), is a first half of the current cycle may be different than thepeak value of the current, i_(L2), in the second half of the currentcycle. The controller 260 may also be configured to adjust a voltage ofthe voltage source 230 and a time between the repeated switch closuresto achieve a desired periodic voltage at V_(O).

Referring briefly to FIG. 5A to FIG. 7B depicted is background materialhelpful to understand the effect of ion current compensation on adistribution of ion energies in the plasma chamber 101. Reference ismade first to FIGS. 5A and 5B in a mode of operation whereI_(L2)=I_(Ion). As shown in FIG. 5A, when a sheath voltage issubstantially constant between pulses, a spread of corresponding ionenergies 570 is relatively narrow to produce a substantiallymonoenergetic ion energy distribution function. Shown in FIG. 5B is anasymmetric periodic voltage function, which may be applied by the biassupply 108 to produce the sheath voltage in FIG. 5A.

Referring to FIGS. 6A and 6B, shown are aspects of sheath voltage, ionflux, and a periodic asymmetric voltage waveform (output by a biassupply) associated with under-compensated ion current. As shown in FIG.6A, when ion current, I_(ion), is under compensated, a sheath voltagebecomes less negative in a ramp-like manner, which produces a broaderspread 672 of ion energies. Shown in FIG. 6B is a periodic voltage thatmay be applied to a substrate support to effectuate the sheath voltagedepicted in FIG. 6A. As shown, the negative ramp-like portion of theperiodic voltage waveform drops with a lower slope than the ramp-likeportion of the period voltage waveform of FIG. 5B (shown as a brokenline in FIG. 6B). Note that such a spread 672 of ion energies may bedone deliberately.

FIGS. 7A and 7B depict aspects of sheath voltage, ion flux, and aperiodic asymmetric voltage waveform (output by a bias supply)associated with over-compensated ion current. As shown in FIG. 7A, whenion current is over compensated, a sheath voltage becomes more negativein a ramp-like manner, which also produces a broader spread 774 of ionenergies. Shown in FIG. 7B, is a periodic voltage waveform that may beapplied to a substrate support to effectuate the sheath voltage depictedin FIG. 7A. As shown, the negative ramp-like portion of the periodicvoltage function drops at a greater rate than the ramp-like portion of aperiod voltage waveform that compensates for ion current (shown as adotted line). Such a spread 774 of ion energies may be done deliberatelyand may be desired.

Referring back to FIGS. 2, 3 and 4, Applicant has found that thecurrent, i_(L2), through L₂, and hence the compensation current, may becontrolled by controlling a pulse repetition rate of the periodicvoltage applied at the output, V_(O), of the bias supply. And the pulserepetition rate may be controlled by the timing of an opening andclosing of the switch. Applicant examined what happened, if after oneturn-on of the switch, the time to the next turn-on was modified. Forexample, Applicant considered what would happens to the applied voltage,V_(O), if the second turn-on of the switch, S, happens slightly earlierin the case where V_(O) is constant between the time periods where theswitch is on. In this case, the second turn-on starts with the sameinitial conditions so the form of the second voltage pulse of theapplied voltage, V₀, should be the same. Because the time between pulsesis now shorter, the average of the applied voltage, V_(O), is higher;thus, the current through L₂ should increase. The increase in i_(L2)increases the downward slope of the applied voltage, V_(O), increasingthe magnitude of the second pulse further. So, increasing the pulserepetition rate is a handle to increase the ion current compensation.This is confirmed through simulation as FIGS. 8-10 show.

Referring to FIG. 8, it is a graph depicting the bias supply outputvoltage, V_(O), and the sheath voltage, Vs, for the circuit of FIG. 2connected to a load as shown in FIG. 3 in which L₁=3 μH, L₂=4 mH,C_(ch)=1.5 nF, C_(S)=1 nF, and I_(ion)=3 A when the voltage source 230,V_(b), provides a DC voltage of 5 kV and the switch is opened and closedto provide a pulse repetition rate of V_(O) at 300 kHz. Operating thecircuit with these parameters results in an initial sheath voltage,V_(S), of −5 kV rising to −2.6 kV because the ion current isunder-compensated. As shown in FIG. 2, the repetition rate of the switchclosing may be the same as the pulse repetition rate of V_(O), And theclosing the switch may be for a time long enough for current I_(L1)through the switch to complete a full cycle from zero to a peak value,back to zero, to a peak value in an opposite direction and back to zero.It should also be recognized that the current I_(L2) may besubstantially constant during a cycle of the periodic voltage at V_(O).

Referring next to FIG. 9, shown is a graph depicting the bias supplyoutput voltage, V_(O), and the sheath voltage, Vs, with the sameparameters as in FIG. 8, except when the voltage source 230, V_(b),provides a DC voltage of 4.5 kV and the switch is opened and closed toprovide a pulse repetition rate of 650 kHz. Operating the bias supplywith these parameters results in a constant sheath voltage of −5 kVbecause the ion current is precisely compensated.

Referring to FIG. 10, shown is a graph depicting the bias supply outputvoltage, V_(O), and the sheath voltage, V_(S), with the same parametersas in FIG. 8, except when the voltage source, V_(b), provides a DCvoltage equal to 4.25 kV and the switch is open and closed to provideV_(O) with a pulse repetition rate of 800 kHz. Operating the circuitwith these parameters results in an initial sheath voltage of −5 kVdecreasing to −5.25 kV because the ion current is over-compensated.

Referring next to FIG. 11 shown is a schematic of circuit of a biassupply that includes a transformer 1160 to couple a periodic voltagefunction to an output 1110 (also referred to as an output node 1110). Asshown, the bias supply includes a voltage source 1130 and an inductor1140 coupled to a switch 1120 and the transformer 1160. A controller1150 is coupled to the switch and the controller is configured to openand close the switch to produce an asymmetric voltage at the output. Theinductor 1140 may be a discrete inductor or part of the leakageinductance of the transformer 1160. For simulation purposes thetransformer is modeled as two perfectly coupled inductors. Parasiticcapacitance between the transformer windings is modeled by C_(W).

FIG. 12 is a graph depicting the bias supply output voltage, V_(O), andthe sheath voltage, V_(S), for the circuit of FIG. 11 connected to aload as shown in FIG. 3 in which L₁=50 nH, L_(P)=56 μH, L_(S)=5.6 mH,C_(W)=1.26 nF, C_(ch)=1.5 nF, C_(S)=1 nF, and I_(ion)=3 A when thevoltage source of the bias supply of FIG. 11 applies 422 VDC and thecontroller opens and closes the switch to produce a periodic voltage atthe output with a pulse repetition rate of 300 kHz. Operating the biassupply with these parameters results in an initial sheath voltage of −5kV increasing to −2.8 kV because the ion current is under-compensated.

FIG. 13 is a graph depicting the bias supply output voltage, V_(O), andthe sheath voltage, V_(S), with the same parameters as in FIG. 12,except when the voltage source of the bias supply of FIG. 11 applies 281VDC and the controller opens and closes the switch to produce a periodicvoltage at the output with a pulse repetition rate of 775 kHz. Operatingthe circuit with these parameters results in a constant sheath voltageof −5 kV because the ion current is precisely compensated.

FIG. 14 is a graph depicting sheath the bias supply output voltage,V_(O), and the voltage, V_(S), with the same parameters as in FIG. 12,except when the voltage source of the bias supply of FIG. 11 applies 212VDC and the controller opens and closes the switch to produce a periodicvoltage at the output with a pulse repetition rate of 1 MHz. Operatingthe circuit with these parameters results in an initial sheath voltageof −5 kV decreasing to −5.24 kV because the ion current isover-compensated.

Referring next to FIG. 15A, shown is a flow chart depicting a methodthat may be traversed in connection with embodiments disclosed herein(e.g., in connection with FIGS. 16A-16D). As shown, a first node of afirst inductor (also referred to herein as a small inductive element) isconnected to a first node of a switch and a second node of the smallinductive element is connected to an output node with a capacitivelycoupled plasma load connected between the output node and a return node(Block 1510). A first node of a first inductor (also referred to a largeinductive element) may be connected to either node of the smallinductive element (Block 1520). As shown, a voltage source is connectedbetween the second node of the switch and the second node of the largeinductive element and either node of the voltage source is connected tothe return node (Block 1530). In operation, the switch is repeatedlyclosed for a time just long enough for the current through the switch tocomplete a full cycle from zero to a peak value, back to zero, to a peakvalue in the opposite direction and back to zero (Block 1540). Inaddition, each of the voltage of the voltage source and the time betweenthe repeated switch closures may be adjusted to achieve a desiredwaveform of a voltage of the plasma load (Block 1550). For example, thedesired waveform may be a sheath voltage to achieve a narrowdistribution of ion energies (e.g., as shown in FIG. 5A) or a broaderdistribution of ion energies (e.g., as shown in FIGS. 6A and 7A).

FIG. 15B is another flow chart depicting a method that may be traversedin connection with embodiments disclosed herein (e.g., in connectionwith FIGS. 16E and 16F). As shown, a first node of a primary winding ofa transformer is connected to a first node of a switch and a first nodeof a secondary winding of the transformer to an output node with acapacitively coupled plasma load connected between the output node and asecond node of the secondary of the transformer (Block 1511). Inaddition, a voltage source is connected between the second node of theswitch and the second node of the primary winding of the transformer(Block 1521). In operation, the switch is closed for a time just longenough for the current through the switch to complete a full cycle fromzero to a peak value, back to zero, to a peak value in the oppositedirection and back to zero (Block 1531). In addition, each of thevoltage of the voltage source and the time between the repeated switchclosures may be adjusted to achieve a desired waveform of a voltage ofthe plasma load (Block 1541). For example, as discussed above, thedesired waveform may be a sheath voltage to achieve a narrowdistribution of ion energies (e.g., as shown in FIG. 5A) or a broaderdistribution of ion energies (e.g., as shown in FIGS. 6A and 7A).

Referring to FIG. 16A, shown is an exemplary bias supply 1601 to apply aperiodic voltage function to a capacitively coupled plasma load 1602(which resides with a plasma chamber, e.g., plasma chamber 101). Theoutput node 1604 of the bias supply 1601 connects to the input node 1605of the plasma load 1602 and the return node 1606 of the bias supply 1601connects to the return node 1607 of the plasma chamber 101. The returnnodes 1606 and 1607 are frequently done through the chassis or enclosureof both the bias supply and the plasma load and since these aretypically kept at ground potential it is also typically referred to asground, chassis ground, or earth ground. As shown, the bias supply 1601utilizes a DC supply 1603 as a voltage source in which the positiveoutput terminal of the DC supply is connected to ground and in which thelarge inductor L2 is connected on the load side of the small inductorL1.

As shown, a first inductor, L1, is coupled between a first node 1670 ofthe switch, S, and the output node 1604, and a first node 1672 of asecond inductor, L2, is coupled to the output node 1604. The voltagesource is coupled between a second node 1674 of the switch, S, and asecond node 1676 of the second inductor, L2. And a connection is madebetween the return node 1606 and the second node 1674 of the switch, S.

Referring to FIG. 16B, shown is an exemplary bias supply 1611 to apply aperiodic voltage function to a capacitively coupled plasma load 1612. Asshown, the bias supply 1611 utilizes a DC supply 1613 in which thenegative output terminal of the DC supply 1613 is connected to groundand in which the large inductor L₂ is connected on the load side of thesmall inductor L₁. As shown, a first inductor, L1, is coupled between afirst node 1670 of the switch, S, and the output node 1604, and a firstnode 1672 of a second inductor, L2, is coupled to the output node 1604.The voltage source is coupled between a second node 1674 of the switch,S, and a second node 1676 of the second inductor, L2, and a connectionis made between the return node 1606 and the second node 1676 of thesecond inductor, L2.

Referring to FIG. 16C, shown is an exemplary bias supply 1621 to apply aperiodic voltage function to a capacitively coupled plasma load 1622. Asshown, the bias supply 1621 utilizes a DC supply 1623 in which thepositive output terminal of the DC supply 1623 is connected to groundand in which the large inductor L₂ is connected on the switch side ofthe small inductor L₁. As shown, a first inductor, L1, is coupledbetween a first node 1670 of the switch, S, and the output node 1604.And a first node 1672 of a second inductor, L2, is coupled to the firstnode 1670 of the switch, S. The voltage source is coupled between asecond node 1674 of the switch, S, and a second node 1676 of the secondinductor, L2, and a connection is made between the return node 1606 andthe second node 1674 of the switch, S.

Referring to FIG. 16D, shown is an exemplary bias supply 1631 to apply aperiodic voltage function to a capacitively coupled plasma load 1632. Asshown, the bias supply 1631 utilizes a DC supply 1633 in which thenegative output terminal of the DC supply 1633 is connected to groundand in which the large inductor L₂ is connected on the switch side ofthe small inductor L₁. As shown, a first inductor, L1, is coupledbetween a first node 1670 of the switch, S, and the output node 1604.And a first node 1672 of a second inductor, L2, is coupled to the firstnode 1670 of the switch, S. The voltage source is coupled between asecond node 1674 of the switch, S, and a second node 1676 of the secondinductor, L2. As shown, a connection is made between the return node1606 and the second node 1676 of the second inductor, L2.

Referring to FIG. 16E, shown is an exemplary bias supply 1641 to apply aperiodic voltage function to a capacitively coupled plasma load 1642. Asshown, the bias supply 1641 utilizes a DC supply 1643 (as a voltagesource) in which the positive output terminal of the DC supply 1643 isconnected to ground and in which a transformer 1644 is used to connectto the plasma load 1642. The transformer includes a primary winding(represented by L_(LP) and L_(P)) and a secondary winding (representedby L_(S) and L_(LS)). A first node 1680 of the primary winding of thetransformer is coupled to a first node 1670 of the switch, S. A firstnode 1682 of the secondary winding of the transformer is coupled to theoutput node 1604. And a second node 1684 of the secondary winding of thetransformer is coupled to the return node 1606. The DC supply 1643(voltage source) is coupled between a second node 1674 of the switch, S,and a second node 1686 of the primary winding of the transformer.

Referring to FIG. 16F, shown is an exemplary bias supply 1651 to apply aperiodic voltage function to a capacitively coupled plasma load 1652. Asshown, the bias supply 1651 utilizes a DC supply 1653 as a voltagesource in which the negative output terminal of the DC supply 1653 isconnected to ground and in which a transformer 1654 is used to connectto the load. The bias supplies 1641, 1651 in both FIGS. 16E and 16F,include a transformer. And as shown, a first node of a primary windingof the transformer is coupled to a first node of the switch, a firstnode of a secondary winding of the transformer is coupled to the outputnode, and a second node of the secondary winding of the transformer iscoupled to the return node. The transformer includes a primary winding(represented by L_(LP) and L_(P)) and a secondary winding (representedby L_(S) and L_(LS)). A first node 1680 of the primary winding of thetransformer is coupled to a first node 1670 of the switch, S. A firstnode 1682 of the secondary winding of the transformer is coupled to theoutput node 1604. And a second node 1684 of the secondary winding of thetransformer is coupled to the return node 1606. The DC supply 1643(voltage source) is coupled between a second node 1674 of the switch, S,and a second node 1686 of the primary winding of the transformer. Asshown, the second node 1686 of the primary winding of the transformer isconfigured to couple to the return node 1607.

The methods described in connection with the embodiments disclosedherein may be embodied directly in hardware, in processor-executablecode encoded in a non-transitory tangible processor readable storagemedium, or in a combination of the two. Referring to FIG. 17 forexample, shown is a block diagram depicting physical components that maybe utilized to realize control aspects disclosed herein. As shown, inthis embodiment a display 1312 and nonvolatile memory 1320 are coupledto a bus 1322 that is also coupled to random access memory (“RAM”) 1324,a processing portion (which includes N processing components) 1326, afield programmable gate array (FPGA) 1327, and a transceiver component1328 that includes N transceivers. Although the components depicted inFIG. 17 represent physical components, FIG. 17 is not intended to be adetailed hardware diagram; thus, many of the components depicted in FIG.17 may be realized by common constructs or distributed among additionalphysical components. Moreover, it is contemplated that other existingand yet-to-be developed physical components and architectures may beutilized to implement the functional components described with referenceto FIG. 17.

This display 1312 generally operates to provide a user interface for auser, and in several implementations, the display is realized by atouchscreen display. In general, the nonvolatile memory 1320 isnon-transitory memory that functions to store (e.g., persistently store)data and processor-executable code (including executable code that isassociated with effectuating the methods described herein). In someembodiments for example, the nonvolatile memory 1320 includes bootloadercode, operating system code, file system code, and non-transitoryprocessor-executable code to facilitate the execution of a method ofbiasing a substrate with the single controlled switch.

In many implementations, the nonvolatile memory 1320 is realized byflash memory (e.g., NAND or ONENAND memory), but it is contemplated thatother memory types may be utilized as well. Although it may be possibleto execute the code from the nonvolatile memory 1320, the executablecode in the nonvolatile memory is typically loaded into RAM 1324 andexecuted by one or more of the N processing components in the processingportion 1326.

The N processing components in connection with RAM 1324 generallyoperate to execute the instructions stored in nonvolatile memory 1320 toenable execution of the algorithms and functions disclosed herein. Itshould be recognized that several algorithms are disclosed herein, butsome of these algorithms are not represented in flowcharts.Processor-executable code to effectuate methods described herein may bepersistently stored in nonvolatile memory 1320 and executed by the Nprocessing components in connection with RAM 1324. As one of ordinarilyskill in the art will appreciate, the processing portion 1326 mayinclude a video processor, digital signal processor (DSP),micro-controller, graphics processing unit (GPU), or other hardwareprocessing components or combinations of hardware and softwareprocessing components (e.g., an FPGA or an FPGA including digital logicprocessing portions).

In addition, or in the alternative, non-transitoryFPGA-configuration-instructions may be persistently stored innonvolatile memory 1320 and accessed (e.g., during boot up) to configurea field programmable gate array (FPGA) to implement the algorithmsdisclosed herein (e.g., including, but not limited to, the algorithmsdescribed with reference to FIGS. 15A and 15B).

The input component 1330 may receive signals (e.g., signals indicativeof current and voltage obtained at the output of the disclosed biassupplies). In addition, the input component 1330 may receive phaseinformation and/or a synchronization signal between bias supplies 108and source generator 112 that are indicative of one or more aspects ofan environment within a plasma processing chamber 101 and/orsynchronized control between a source generator and the single switchbias supply. The signals received at the input component may include,for example, synchronization signals, power control signals to thevarious generators and power supply units, or control signals from auser interface. Those of ordinary skill in the art will readilyappreciate that any of a variety of types of sensors such as, withoutlimitation, directional couplers and voltage-current (VI) sensors, maybe used to sample power parameters, such as voltage and current, andthat the signals indicative of the power parameters may be generated inthe analog domain and converted to the digital domain.

The output component generally operates to provide one or more analog ordigital signals to effectuate the opening and closing of the switch andcontrol of the voltage sources described herein.

The depicted transceiver component 1328 includes N transceiver chains,which may be used for communicating with external devices via wirelessor wireline networks. Each of the N transceiver chains may represent atransceiver associated with a particular communication scheme (e.g.,WiFi, Ethernet, Profibus, etc.).

As will be appreciated by one skilled in the art, aspects of the presentdisclosure may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present disclosure may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present disclosure may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

As used herein, the recitation of “at least one of A, B or C” isintended to mean “either A, B, C or any combination of A, B and C.” Theprevious description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the present disclosure.Various modifications to these embodiments will be readily apparent tothose skilled in the art, and the generic principles defined herein maybe applied to other embodiments without departing from the spirit orscope of the disclosure. Thus, the present disclosure is not intended tobe limited to the embodiments shown herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A bias supply to apply a periodic voltagecomprising: an output node; a return node; a switch; a first inductorcoupled between a first node of the switch and the output node; a firstnode of a second inductor coupled to one of the output node or the firstnode of the switch; a voltage source coupled between a second node ofthe switch and a second node of the second inductor; a connectionbetween the return node and one of the second node of the switch and thesecond node of the second inductor; and a controller configured to causean application of the periodic voltage between the output node and thereturn node by repeatedly closing the switch for a time just long enoughfor current through the switch to complete a full cycle from zero to apeak value, back to zero, to a peak value in an opposite direction andback to zero.
 2. The bias supply of claim 1, wherein the controller isconfigured to adjust a voltage of the voltage source and a time betweenthe repeated switch closures to achieve a desired periodic voltage. 3.The bias supply of claim 1, wherein the controller includes at least oneof a processor or a field programmable gate array and the controllerincludes non-transitory computer-readable medium comprising instructionsstored thereon, for execution by the processor, or for configuring thefield programmable gate array, to control operation of the switch.
 4. Abias supply to apply a periodic voltage comprising: an output node; areturn node; a switch; a transformer, a first node of a primary windingof the transformer coupled to a first node of the switch, a first nodeof a secondary winding of the transformer coupled to the output node,and a second node of the secondary winding of the transformer coupled tothe return node; a voltage source coupled between a second node of theswitch and a second node of the primary winding of the transformer; anda controller configured to: cause an application of the periodic voltagebetween the output node and the return node by repeatedly closing theswitch for a time just long enough for current through the switch tocomplete a full cycle from zero to a peak value, back to zero, to a peakvalue in an opposite direction and back to zero.
 5. The bias supply ofclaim 4 wherein the second node of the switch is coupled to the returnnode.
 6. The bias supply of claim 4, wherein the second node of theprimary winding of the transformer is coupled to the return node.
 7. Thebias supply of claim 4, wherein the controller includes at least one ofa processor or a field programmable gate array, and the controllerincludes a non-transitory computer-readable medium comprisinginstructions stored thereon, for execution by the processor, or forconfiguring the field programmable gate array, to control operation ofthe switch.
 8. A plasma processing system comprising: a plasma chamberincluding: a volume to contain a plasma; an input node; and a returnnode; and a bias supply including: a switch; a first inductor coupledbetween a first node of the switch and the input node of the plasmachamber; a first node of a second inductor coupled to one of the inputnode of the chamber or the first node of the switch; a voltage sourcecoupled between a second node of the switch and a second node of thesecond inductor; a connection between the return node and one of thesecond node of the switch or the second node of the second inductor; andmeans for controlling the switch and voltage source to achieve a desiredwaveform of a voltage of a plasma load when the plasma is in the plasmachamber.
 9. The plasma processing system of claim 8, wherein the meansfor controlling includes means for adjusting the voltage of the voltagesource and a time between repeated switch closures to achieve thedesired waveform of the voltage of the plasma load.
 10. The plasmaprocessing system of claim 8, wherein the means for controllingincludes, for each closure of the switch, means for closing the switchfor a time just long enough for current through the switch to complete afull cycle from zero to a peak value, back to zero, to a peak value inan opposite direction and back to zero.
 11. The plasma processing systemof claim 8, wherein the return node comprises a ground return.
 12. Aplasma processing system comprising: a plasma chamber including: avolume to contain a plasma; an input node; and a return node; and a biassupply including: a switch; a transformer, a first node of a primarywinding of the transformer coupled to a first node of the switch, afirst node of a secondary winding of the transformer coupled to theinput node of the plasma chamber, and a second node of the secondarywinding of the transformer coupled to the return node; a voltage sourcecoupled between a second node of the switch and a second node of theprimary winding of the transformer; and means for controlling the switchand voltage source to achieve a desired waveform of a voltage of aplasma load when the plasma is in the plasma chamber.
 13. The plasmaprocessing system of claim 12, wherein the means for controllingincludes means for adjusting the voltage of the voltage source and atime between repeated switch closures to achieve the desired waveform ofthe voltage of the plasma load.
 14. The plasma processing system ofclaim 12, wherein the means for controlling includes, for each closureof the switch, means for closing the switch for a time just long enoughfor current through the switch to complete a full cycle from zero to apeak value, back to zero, to a peak value in an opposite direction andback to zero.
 15. The plasma processing system of claim 12, wherein thesecond node of the switch is coupled to the return node.
 16. The plasmaprocessing system of claim 12, wherein the second node of the primarywinding of the transformer is coupled to the return node.
 17. The plasmaprocessing system of claim 12, wherein the wherein the return nodecomprises a ground return.